ChemPhotoChem最新文献

Two π-extended derivatives of boron-dipyrromethene (BODIPY) – unsymmetrical benzo[b]-fused BODIPY 1 and symmetrical naptho[b]-fused BODIPY 2 – were synthesized. Spectroscopic and photophysical properties of the synthesized fluorescent dyes were investigated in various organic media. Both BODIPY 1 and BODIPY 2 distinguished by bathochromically shifted absorption and emission bands compared to their non-fused derivatives, while possessing green (526–543 nm) and red (664–708 nm) absorbance and fluorescence, respectively. Spectral characteristics of the investigated fluorescent dyes were found to be weakly depended on solvent polarizability in case of BODIPY 1 and greatly influenced by both solvent polarizability and dipolarity in case of BODIPY 2. Quantum chemical calculations were used to clarify the relationships between geometry/electronic structure and spectral properties/solvatochromic behavior of BODIPY 1 and BODIPY 2.

With the rise of antibiotic resistance within clinical settings, combating the growth of microbial biofilms presents a unique challenge. Biofilm-inhabiting bacteria are embedded within a self-produced, protective matrix, which can reduce the efficacy of treatment. The naturally derived product β-lapachone is an appealing therapeutic agent that has been reported to inhibit biofilm growth. However, its off-target toxicity and poor metabolic stability pose a significant hurdle for its application in vivo. Using a photo-pharmacological approach via a coumarin-based photocage, the reactivity of β-lapachone can be tuned so it only becomes active once the photocage is removed. Here we report both the photo-uncaging efficiency and the effective inhibition concentration of photocaged β-lapachone within model Bacillus subtilis biofilms. Additionally, the mechanism of action is analyzed with results supporting catalase inhibition. This novel light-activatable anti-microbial has potential applications in medical settings to inhibit biofilm growth and provide synergistic treatment with traditional antibiotics.

Constructing a catalyst capable of reducing CO₂ through photoreduction in aqueous environments presents a significant challenge. In this study, we present the synthesis of BiVO₄@NiCo₂O₃ heterojunction using a straightforward hydrothermal method for CO₂ photoreduction. The sample with the optimal loading ratio demonstrates a CO generation rate of 7.202 μmol ⋅ g⁻¹ ⋅ h⁻¹, which is twice that of pure BiVO₄ (3.626 μmol ⋅ g⁻¹ ⋅ h⁻¹) and 1.5 times that of pure NiCo₂O₃ (4.726 μmol ⋅ g⁻¹ ⋅ h⁻¹). Analysis using XPS and EPR techniques suggests that electron transfer at the interface of the heterojunction facilitates the separation of photogenerated charge carriers, thereby enhancing the efficiency of the photocatalytic process. This investigation offers a viable approach for developing photocatalysts for CO₂ reduction in aqueous environments.

Visible light-mediated photocatalytic approach for the radical functionalization of alkenes bearing the fluorinated aryl sulfide fragment is described. The process occurs in the presence of organic photocatalyst using sulfinates as sources of radicals. The key step of the reaction is the intramolecular 1,4-migration of the polyfluoroaryl group. In the reaction, three new bonds are formed (two C−C and one C−S bond). The decisive role of fluorine atoms in the reaction efficiency was confirmed by DFT calculations.

Photoelectrocatalytic (PEC) reduction of nitrobenzene (NB) is an extremely promising technology for renewable energy utilization and conversion. PEC reduction of NB to produce higher-value azobenzene (AZB) instead of aniline (AN), which is now commonly reported, is not currently achievable. In this work, we fabricated Ag nanoparticles (AgNPs)-decorated silicon nanocone (SiNC) array photocathodes with which the PEC reduction of NB to azobenzene (AZB) was realized for the first time. The SiNC array structure constructed by cryogenic dry etching greatly improved the light absorption ability of the photoelectrode. Ag was chosen as the cocatalyst because of its larger potential difference for the NB reduction reaction and the competing side reaction hydrogen evolution reaction. The Schottky junction formed by AgNPs with Si facilitates the rapid extraction of photogenerated electrons to participate in the PEC reaction. Under the optimized conditions, the PEC reduction of NB was achieved with a conversion of more than 90 %, with the reduction products being mainly AZB (9 : 1 ratio of AZB to AN) as well as excellent stability. The present work provides a photoelectrode that highly selectively PEC reduction of NB to AZB, and also provides insights into the design and preparation of high-performance silicon-based photoelectrodes.

The Front Cover illustrates the photophysical relaxation mechanisms of archetypal aromatic/antiaromatic molecules, starting from low-energy excited states, and their rationalisation in terms of electronic descriptors that allow quantifying the extent to which the formation of biradicaloid structures affects the crossing of the potential energy surfaces. More information can be found in the Research Article by Jesús Jara-Cortés et al. (DOI 10.1002/cptc.202300291).

Hot exciton emitters based on 9,10-substituted anthracenes are a well-investigated class of molecules featuring thermally activated delayed fluorescence (TADF). TADF converts triplet excitons into singlet excitons and improves the internal quantum efficiency of electroluminescent devices to performance beyond the limit of spin-statistics of conventional emitters. In this paper, we compare different 1,8-functionalized donor/acceptor-substituted anthracenes and compare these to established 9,10-functionalized hot exciton emitters. Interestingly, our new 1,8-substituted anthracenes make use of a beneficial hot exciplex pathway, resulting in improved emission characteristics and higher photoluminescence quantum yield.

The electronic structure and photophysical properties of several acrylaldehyde-bridged deazaflavin derivatives (cFLs) were investigated theoretically. The impact of acrylaldehyde bridging on photophysical properties of deazaflavin (cFL) is strongly site-dependent. Specifically, the change of adiabatic energy of electronic transitions(ΔE_ad) and vibronic coupling promote fluorescent emission to be comparable to internal conversion of cFL and cFL4 (both C5−C6 and C9−N10 bridged, but C9−N10 bridged by propene), turning them eligible as fluorescent sensors. As El-Sayed's rule is satisfied in cFL1(C5−C6 bridged), cFL2(C9−N10 bridged) and cFL3(both C5−C6 and C9−N10 bridged), intersystem crossing from first singlet excited state to triplet excited states (T_n) become dominant and the evolution of excited cFLs from T₁ appears vital. The rate constants of photophysical processes indicate these cFLs are of dominantly high steady state T₁ concentration and are potential triplet sensitizers. We expect the findings would pave the way for rational design of novel cFLs with extraordinary photophysical properties.

Luminescent metal halides, as a type of luminescent semiconductor material, offer advantages that fulfill the requirements of emerging light source devices, such as high luminescence efficiency, good thermal stability, and tunable colorful emission. Blue light being one of the three primary colors plays a crucial role in the field of lighting and colorful displays. However, the progress in device performance of blue-light materials lags behind that of green and red-light materials. Currently, there have been numerous reports on metal halide perovskite blue-light materials, but a comprehensive review on the development and performance control of blue-light metal halides is yet to be found. This paper provides a comprehensive summary of the design strategies and luminescence mechanisms of blue-light perovskites with various luminescence centers, as well as their application progress in the fields of light-emitting diodes (LEDs), X-ray scintillators, information anti-counterfeiting and encryption. It also explores possible directions for subsequent performance improvement. This work aims to offer valuable insights and recommendations for the future development of blue-light metal halides, with significant implications for the fabrication of novel blue light devices and advancements in detection technology.

Norbornadiene/Quadricyclane (NBD/QC) is a prototypical bridged bicyclic diene (BBD)-based photoswitch that has been well-studied for molecular solar thermal energy storage (MOST). Inspired by the recent synthetically accessed BBDs, herein several photoswitches are rationally designed with modulated ring strain energies (RSE) in photoisomers to incorporate high energy storage density (ESD) and storage time in a single couple. The storage energy ($$) calculated at DLPNO-CCSD(T)/Def2TZVP level is correlated with difference in RSE of two isomers (ΔRSE) whereas thermal back reaction (TBR) barrier calculated at (8,8)-CASPT2/6-311++G** shows correlation with RSE in metastable photoproduct. On the basis of these structure-property-RSE relationships, we recognized that two photoisomers need not to be highly strained. Instead, the RSE in the photoproduct and diene should be minimized while maintaining a large enthalpy difference between them to increase ESD and extend energy storage times in a single photoswitch. TBR barrier is governed by RSE in photoproduct and increasing strain in photoproduct may improve the $$ but at the cost of the TBR barrier. Herein, the structural skeletons are explored that holds promise to remarkably improve thermochemical properties relative to the unsubstituted BBD-based photoswitches reported so far. The BBD molecules with short saturated bridge length but elongated unsaturated bridges could bestow desirable thermochemical parameters and can be regarded as excellent candidates for MOST application. The work lays a theoretical foundation that guides to improve thermochemical properties via strain engineering of BBD-based photoswitches and opens a new avenue for designing principles and future experimental investigations of MOST systems.